[Equest-users] Tank less DWH

[Nicholas Caton via Equest-users]

I don’t believe I’ve ever documented 30-40% Service Hot Water savings on unitary heating equipment alone.  Either your designer/manufacturer must also be counting on serious reductions with low flow fixtures, or somebody is trying to sell something...

The Appendix G Table G3.1 will direct you back towards the table at the end of the Service Water Heating section in 90.1 for direct guidance on what the baseline case should reflect in relation to your proposed case instantaneous heaters.  Looks like for your make/model you’ll be needing to address both thermal combustion efficiency AND determine standby losses based upon the capacity of the unit cited.

I’d advise caution before immediately entering “n/a” for proposed case standby losses in your LEED documentation.  Consider whether in fact there is a storage tank somewhere, or other opportunities outside of combustion and piping distributions for heat to leave the system.

For the proposed case side, I might poke the manufacturer (time allowing) to provide you a thermal efficiency (combustion + condensate recovery) at a sampling of firing rates for a given delta (ground water --> delivery temp), and use that data to evaluate whether the library curves eQUEST assigns for instantaneous gas boilers is in alignment or otherwise needs tweaking.  If you don’t have time to dive this far I’d simply be mindful to ensure baseline + proposed case curves are at least matching.

Hope that helps!

~Nick

[cid:image001.png at 01D2E912.F83239D0]
Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Regional Energy Engineering Manager
  Energy and Sustainability Services
  Schneider Electric

D  913.564.6361
M  785.410.3317
F  913.564.6380
E  nicholas.caton at schneider-electric.com<mailto:nicholas.caton at schneider-electric.com>

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[cid:image002.png at 01D2E912.F83239D0]



From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Morteza Kasmai via Equest-users
Sent: Monday, June 19, 2017 10:54 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Tank less DWH

Hello, everyone

I am trying to model a new DWH (Intelli-hot system Gen-II-iQ1501) for a mid-rise residential building. This is a high-output, on-demand water heater, which eliminates storage tank, standby losses, and mixing valves. Per the manufacturers and the project’s engineer notes, expected savings on hot water for this type of WH compare to a regular storage tank WH is 30% to 40%. I am wondering what type of WH should I select for the Baseline Case in order to comply with ASHRAE/LEED energy modeling protocol.

Your thoughts and suggestions would be highly appreciated,
Morteza


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